As a route calculation device which calculates a route (avoidance route) for avoiding an obstacle or the like, existing in a path, a device described in International Patent Publication No. WO2013/051081 is known. The device described in the same document performs calculation of a route for avoiding two objects to be avoided having been detected in a traveling direction of a vehicle on which the device is mounted in the following procedures.
First, a first avoidance route, which is a route of the vehicle capable of avoiding contact with a first object to be avoided, or the headmost object to be avoided, is calculated from the positional relationship between the first object to be avoided and the vehicle, the momentum (speed, deceleration, that is, deceleration g-force, yaw rate, and the like) of the vehicle at the time of starting the avoidance travel, and the momentum changing ability of the vehicle. Subsequently, a point where the distance from the first object to be avoided starts to change from a decrease to an increase on the calculated first avoidance route is obtained as a point where the avoidance of the first object to be avoided is completed. Further, from the positional relationship between the obtained avoidance completion point and a second object to be avoided, which is the next object to be avoided, the predicted momentum of the vehicle at the avoidance completion point, and the momentum changing ability of the vehicle, a second avoidance route, which is a route of the vehicle capable of avoiding the second object to be avoided, is calculated with the avoidance completion point as the starting point. Then, a route including the first avoidance route to the second avoidance route is obtained as a route for avoiding the two objects to be avoided.